Mobile mixers of the type carrying spray of other delivery means for concrete or thelike



2,880 976 MOBILE MIXERS OF THE TYPE CARRYING SPRAY 4 Sheets-Sheet 1 April 7, 1959 M. M. TRUE OF OTHER DELIVERY MEANS FOR CONCRETE OR THE LIKE Flled Jan 12, 1956 FIG. 2

INVENTOR MAX M TRUE I 4 ATTORNEZL April 7, 1959 TRUE 2,880,976

MOBILE MIXERS OF THE TYPE CARRYING SPRAY OF OTHER DELIVERY MEANS FOR CONLRETE OR THE LIKE Flled Jan 12, 1956 4 Sheets-Sheet 2 |NVENTOR MAX mu:

ATTORNEY Apr1l 7, 1959 M. M. TRUE 2,880,976

- MOBILE MIXERS OF THE TYPE CARRYING SPRAY OF OTHER DELIVERY MEANS FOR CONCRETE OR THE LIKE Flled Jan 12 1956 1 4 Sheets-Sheet 3 E M m w m M .N

, ATTORNEYX:

M. TRUE MOBILE MIXERS OF THE TYPE" CARRYING SPRAY April 7, 1959 M OF OTHER DELIVERY MEANS FOR CONCRETE OR THE LIKE 12, 1-956 F 4 Sheets-Sheet 4 Filed Jan.

R o T N E V N MAX /1.TRU

a ATTORNZ United States Patent MOBILE MIXERS OF THE TYPE CARRYING SPRAY OF OTHER DELIVERY MEANS FOR CONCRETE OR THE LIKE Max M. True, Tulsa, Okla.

Application January 12, 1956, Serial No. 558,765

11 Claims. (Cl. 259-451) This invention relates to mobile mixers of the type that carry spraying or other delivery means for concrete or the like spray materials and add the required water to the mix prior to delivery to the place of application of the wet material to the building construction.

The present spraying system and method is an improvement over previous methods, which usually added the water to the dry mixture at the spray nozzle, thus causing incomplete mixture of improper proportions of water with the solid ingredients, and required experienced operators; and even then, these methods were very inefiicient and wasteful of water and compressed air.

In the event the water was added to the mixture before delivery through conduits to the spray nozzle, mixtures of low moisture content were difiicult to force through the conduits and would often pack in bends or elbows,

2,880,976 Patented Apr. 7, 1959 the above process by using a horizontally mounted common rotor shaft extending through both tanks and having peripheral mixing blades mounted thereon to thoroughly mix and sweep the correctly proportioned wet mixture in each tank in a circulatory path toward the adjacent ends of the tanks at the periphery and in the opposite axial direction at the center, so as to continuously feed the mixture past the sump outlets of the tanks at their adjacent ends, the two sumps being connected to a selector valve for selectively opening one of the sumps to the spray delivery hose while closing the other sump, so as to enable the corresponding tank to be reloaded and mixed while the other one is sealed and used for supplying the slugs of the mixture under pressure through the sump to the delivery hose, thus providing a continuous supply of freshly mixed wet mixtures to the spray nozzle upon demand.

A further object is to provide piping assemblies for the above system comprising an air inlet from the compressor connected through a cut-off valve and three Ts in series to the pressure chamber of a pressure control valve, the first T serving as a connection to a quick hose coupling for the air hose to the gun, the second T being connected to the inlet of the pressure control valve, and the third T being connected to a bleed valve for controlling the pressure in the pressure chamber, to which the compressed causing interruptions in the work while the packs were I cleared.

If the water was not added until the mixture reached the nozzle, 21 lot more air was required to blow the dry ingredients through the conduits to the nozzle where dusting would also occur.

The main object of the present invention is to make it possible to efiiciently handle wet mixtures of low moisture content after they have been thoroughly mixed with the correct proportion of water, and deliver'them in a desired spray for application to reinforced concrete layer construction or the like.

A further object is to mix the proper proportion of water with the dry ingredients in a mobile mixer, and facilitate the delivery of slugs of this correct mixture from the mixer to the sprayer through a conduit by introducing ai-r'under pressure in controlled amounts to the top of the mixed batch in the mixer or to the conduit connection at the bottom of said mixer, or both, depending on the fluidity of or degree of moisture in said mixture. 4

A further object is to control the metering of the compressed air mentioned above, at the nozzle station, so that inexperienced men can handle the sprayer and do not require someone else to adjust their spray by means of controls located at the mixer.

A further object is to use a metering valve which is responsive to the pressure controlled by a bleed valve connected to a control pressure chamber supplied from a constant pressure source through an adjustable inlet, said valve and chamber being located at the mixer, and'said bleed valve, at the spray nozzle and connected by a flexible tube to said pressure chamber.

A further object is to use a fine needle control valve for the above adjustable inlet.

i A further object is to use additional compressed air connected directly to the spray nozzle to improve spraying of the slugs evenly over the work.

A further object is to provide piping assemblies and mixer blades on the mobile mixer to facilitate carrying 70 A further object is to provide means including apiping' out the above objects.

system for a two tank mobile mixer to adapt it for use inair is supplied through a cut-off valve in the connection between the second and third Ts, the outlet from the pressure control valve being connected through another T to the air inlets of front and rear piping assemblies, and a water inlet adapted for coupling to a water supply and connected through a T, a cut-off valve and a flow meter in series to another T for connection to the water inlets of the front and rear piping assemblies, which are mounted adjacent the front and rear tanks of the mobile mixer, the T nearest the water supply being also connected to afaucet.

A further object is to mount similar water and air supply and control assemblies at the front and rear of the above mixer, each comprising a connection from the air inlet through an air cut-off valve and a T, in series to the inlet of a 3 way proportioning valve, the T being also valve into the side of the corresponding sump connection opposite its outlet.

A further object is to provide hose connections between the other connections of the Ts connected to the air inlets and the water inlets of front and rear piping assemblies together for parallel operation, and to, provide panels on the housings over the front and rear assemblies on which the corresponding proportioning and air cut-off valve control knobs, may be mounted; and to provide a pressure gauge connected to the pressure control chamber and visible from the nozzlemans station where the bleed valve is mounted at the nozzle and is connected to the third T above referred to, by flexible tubing.

Other and more specific objects will become apparent in the following detailed description of one form of the invention as illustrated in the accompanying drawings, wherein:

Fig. 1 is a perspective view of a portable mixer incor-' porating the present invention,

Fig. 2 is a sectional view through one of the tanks showing the general shape of the mixing blades and loca tion of the sump connection,

Fig. 3 is a perspective view, partly in section, and broken away, of the sump piping connections,

Fig. 4 is a perspective view of the front piping assembly,-

- with air and water supply controls,

'Fig. 5 is a perspective view of the rear piping assembly,

'Fig. 6 is an enlarged perspective view of the pressure control or metering valve assembly, and

Fig. 7 is a perspective view of the nozzle in action.

.As a result of the useof spraying systems of the prior art, the concrete structural jobs performed were plagued with tendency to form sand-pockets beneath and around closely placed reinforcing, and the water-cement ratio seemed to vary considerably giving a variance in color, texture and in strength.

The present system has not only eliminated these defects but is free of failures by clogging of the delivery conduits and is much more economical to make and to operate. It provides good embedment of the reinforcingboth on vertical walls and horizontal slabs. Metered water and thorough premixing have been found to be essential to elimination of sand pockets and rebound.

1 For purposes of illustration the present system is applied to a dual-tank mobile mixer such as shown in Fig. 1, having rotating mixer blades 10 on a horizontal shaft 11 incoextensive substantially cylindrical tanks 12 and 13 extending longitudinally of the mobile chassis 14 and having their sumps 15 and 16 at adjacent ends of the tanks connected to ports 17 and 18 in a common valve plate 19 leading through a selector slide valve to a conduit or hose 20,.f0r delivery to the spray nozzle 21. The tanks are provided with independent manhole covers 22 .or doors on top for charging the dry ingredient batches therethrough and sealing them for operation under pressure selectively, so that continuous nozzle operation is available by premixing a batch in one tank while the material valve lever 23 is moved in a position to open the sump of the other .tank to supply thedemands of the nozzle operation.

Although it was necessary in previous nozzle construcfions to use compressed air fed directly to the nozzle for breaking up and distribution of the material in the spray, the present system requires only a plain swedge shaped nozzle (not shown) which may be operated by inexperienced .nozzlemen, because the air under pressure is supplied in correct proportions to the top of the mixture in the tank and to the corresponding sump connection in accordance with the flowability of a correct low moisture content well-mixed concrete or other cement mixture, and the mixer blades passing over the sump provide an intermittent supply of the mixture and top air into the sump, while the sump air is added in sufiicient quantity under pressure to move the slugs of the mixture through the conduits and to break them up at the nozzle into a homogeneous spray.

In order to provide this control and delivery of the perfectly proportioned and mixed materials through the nozzle I have inserted a nipple 24 into each sump as shown which allows a flow of air through this point when required. This is accomplished by the means of a proportioning valve 25. The purpose and accomplishment of this improvement is as follows: Whereas previous guns would not flow a real dry concrete or a real coarse aggregate because they plug up the sump from air pressure pushing down on them, in the present gun the use of the bottom sump air in combination with the top air allows me to blow any material from a complete dry state down the line to as much water content as is desired. In other words, when I blow a wet material, I use top air only, and when I use a dry material I use bottom air with a small amount of top air to keep the material from floating in the tank. This works very nicely with no plug-up in the sump.

I have also changed the paddles, disclosed in my prior patent application Ser. No. 461,483 for Mobile Mixer, now US. Patent No. 2,788,197 to further aid the gunning of this dry material. In other words, the paddles 10 act as a distributor and actually deliver small amounts or slugs of material into a rapid-moving stream of air in the sump causing a very slight pulsation in the hose line, which is very important in keeping the materials from teed concrete. This is well known, the previous type guns or dry mix guns that are on the market, cannot do as they guess at the required water at the nozzle, which produces a guess water mix. As is well known, concrete is largely a water-cement ratio mixture. It takes a certain amount of water for hydration of the cement in the concrete, and then any excess of the water causes voids in the concrete or weakens it so that with my gun -I can establish the water-cement ratio because I measure the water exactly in the dual tank chambers. This is readily acceptable to any concrete engineer or architect over previous types of guns. This also eliminates any sand pockets behind reinforcing steel, which is very frequently the case with the dry mix type of guns, because they have a poor mix; as in the premix or wet mix each particle of aggregate is surrounded by cement paste and eliminates any possibility of sand pockets.

Also through a wet mix gun like mine, I eliminate rebound. Rebound is caused because of a very poor mix of water and aggregate in the tanks and thus we eliminate rebound.

The important feature of my gun over the previous guns is that they require a dry sand to go through their hose, and if too wet it will plug the hose. My machine does not require a dry sand but will shoot any sand whether dry, medium or wet. This is accomplished by reducing the amount of water running into the tank.

Also my gun does not require a large compressor like the previous types of guns. A compressor of c.f.m. of the Gile flow type, like Ingersoll-Rand manufactures, islarge enough for the present gun. The previous type of gun requires a 500 or 600 c.f.m. compressor, consequently I can place concrete with an investment, including the truck, compressor, conveyor, and the complete machine, for about $12,000.00, compared to the previous type of guns with their 500 c.f.m. compressor which costs about $15,000.00 by itself, and requires a concrete mixer, as they do not mix their material in the machine like mine, also a large truck and gun, which investment is around $30,000.00 for comparable capacity.

Previous types of guns use all volume of air for conveying. The present gun uses a combination of air pressure and volume, therefore less volume of air is required. To further explain the proportioning selector valve 25, this valve allows either a top air or complete bottom air, or any fraction of either one, or a combination of both. I call this a selector valve. You will also note in the drawings that I have two panels, 26 and 27, one for each tank. The top valve 25 is the selector valve, or proportioning valve, as it is set every day for the type of material you are shooting. If it happens to be a wet material, you use top air. If it is dry material, you use about 75% bottom air and 25% top air. This of course really simplifies the operation of this machine. The water is fed from a water hose connected to a coupling 28 through the piping shown in Fig. 4, the cut-01f valve 29, the flow meter 30, the T fitting 31, the check valve 32 in either front or rear piping assembly, T fitting 33, and then through the selector valve .25. A hose 34 may be used to interconnect the two T fittings 31 in the front and rear pipe assemblies. The check valve 32 stops the water from going into a tank that is under pressure also because of the air pressure, and the water runs into the other tank which is desired.

Referring to the metering valve assembly, Fig. 6, you will notice a regulator coupling 35 that requires a inch air hose 55, shown in Fig. 7, leading to the gun nozzle, whereby the air in the tanks can be lowered and raised by the gun operator. Without this hose the air supply pressure may be adjusted by a bleed valve 36 which bleeds off the air pressure regulator, which allows this fluctuation. With the hose, valve 36 is left fully opened and the bleeding is adjusted by a valve at the end of this hose. This is done by the gun man, who then has complete control of the operation in the amount of flow of material required. For an inexperienced gun man, it might be better not to use this hose and let him depend on another experienced man at the machine to control the amount of flow by operation of the valve 36.

. By proper adjustment of selector valve 25, both bottom air, and top air is used to blow a low moisture content material such as concrete to refractories of 8% moisture approximately. Bottom air permits the material to move out of the sump. Top air feeds the sump and produces slugs of material intercepted by volumes of compressed air. Without bottom air the sump will pack, without top air the material will float. So therefore a combination of bottom and top air is required. The paddles 37 operating over the sump act as a distributor and permit intermittent feeding of slugs of material and air. Thus the hose will not plug up and when the material valve is shut off at the tank the hose is emptied by the continued flowof compressed air through the sump. A nozzle with added air is not necessary as the air introduced in the hose between the material wads is suflicient to break up the material in a nice spray and only a swedge pipe is required.

The top air is used for pushing by pressure a material that flows through the hose. The combination top and bottom air carries the harder flow or low moisture content material through the hose in a volume method of wads of material and pockets of air. This is accomplished by a selector or proportioning valve 25. We eliminate dusting and rebound that is common in other known sprayer systems, because of premixing.

This machine will blow material of any low moisture content down to a perfect dry by using the combinations of air mentioned.

The nozzle man does not have to have any control over the quality of the concrete because it is controlled at the machine. Therefore a trained man is not necessary. The nozzleman, in some known systems, adds the water at the nozzle and has a guess control of the quality of the concrete. An experienced nozzleman is therefore required to operate that type of machine. Usually 2 to 3 years experience is necessary.

The present machine will sand blast wet or dry by using a regular sand blast nozzle.

Due to the slugs of properly premixed material, it traps the air and conserves it. Accordingly, only a 125 c.f.m. air compressor is required to blow the material through the 1%" hose where some other systems 'have to have a compressor 4 or 5 times this capacity. The so called dry mix guns of the prior art carry their material through in a dry state and mix water at the nozzle, therefore they waste a considerable amount of the air and require a 500 c.f.m. air compressor to do the same volume of work as the present sprayer system.

The premixing gives controlled concrete. Others guess at the water supply at the nozzle and do not have controlled installations. I can use wet sand, others have to dry their sand for sand blasting or for concrete work. They pick up drift or sand pockets in the concrete, shooting around reinforcing steel, because of the poor mix. The premixing eliminates sand pockets.

Each pipe assembly on the front and rear of the machine is similarly operated and constructed. The selector valve 25 is a 3-way valve with two adjustable ports to the tank and sump lines, respectively, to provide variations in the amounts of their opening, or to close one or the other entirely, while maintaining the supply port at the bottom of the valve open all the time. The hand wheel valve 38 is a cut-off valve for the compressed air which is supplied from the compressor by a hose line connection through main air supply valve 39 and the regulator or metering valve assembly, shown in Figs. 6 and 4, to the cut-off valve 38 in each pipe assembly, by means of the T-fitting 40 (Fig. 4). A hose line 41 may be connected between this T-fitting 40 and the cut-off valve 38 in the rear pipe assembly. A safety pressure relief 42 may be provided in the air supply line with a manual relief control 43 which may have a pull string tied to it and extended to a convenient place on the front control panel 27 for operation therefrom. A pressure gauge 44 may also be suitably mounted on this panel for indicating the regulated air pressure delivered to the air supply line, the regulation of this pressure being provided, as already mentioned, by the bleed valve 36. Check valves 45 are provided in the lines from the selector valves to the tanks to prevent return leakage from one tank back through the pipe assemblies to the other tank to interfere with the water feeding into the latter, when the air supply is cut off from both tanks.

The flowmeter 30 has a continuous indicator dial 46 to enable the operator to supply measured amounts of water to the mixes as may be required.

The regulator has a metering valve 47, with an air inlet 48 and outlet 49, and is responsive to the pressure in a control chamber to which air is supplied through the valve 50 and from which it is bled by means of the bleeder valve 36.

A quick coupling fitting 51 for an air hose (not shown) to the gun or other use, may be connected into the main air supply line as shown.

Fig. 7 ilustrates a plain nozzle 21 in use in applying a premixed material 53 to a reinforced wall construction 54. A hose 55 may be connected to the coupling 35 at the bleeder valve 36, and provided at its nozzle end with a bleeder valve 36' for adjustment by the operator 56 when it is desired to change the air pressure.

Many obvious modifications in the form and arrangement of the parts may be made without departing from the spirit and scope of this invention, as defined in the appended claims.

What is claimed is:

l. A system of spraying concrete mixtures of various moisture content and the like, comprising a pair of coextensive horizontal substantially cylindrical mixing tanks having adjacent sumps, a selector valve connected to said sumps, a common flexible delivery tube having an inlet end connected to said selector valve and a spray nozzle at its outlet end, for delivering the mixture from said selector valve to said spray nozzle, means for supplying compressed air in any proportions to the top of the tank from which the mixture is being delivered, and to the sump of said tank, means for providing intermittent mechanical pulses in the flow of said mixture into said sump past said air supply means thereto, to form slugs of said mixture, said means supplying the compressed air to said sump in slugs between said slugs of mixture, said air pressure being suflicient to facilitate the delivery of mixtures of low moisture content.

2. A system as defined in claim 1, and control means to proportion the supply of compressed air to the top of the tank and to the sump in accordance with the fluidity of the mixture as may be required to prevent plugging up the delivery tube, said selector valve being operable to cut off either sump while fully opening the other to the inlet end of said delivery tube.

3. A system as defined in claim 1, and means for regulating the pressure of said compressed air.

4. In a wet mixture spraying system such as defined in claim 1, said tanks extending from front to rear on a portable cart frame, a front and rear piping assembly, each comprising a compressed air supply line having a cut-off valve and a three-way valve with two outlet ports for proportioning the amounts of air to the top of the corresponding tank and to its sump respectively, and connecting piping from each of these outlet ports through 7 'aclre'ck valve to its respective destination "toprevent back flow.

5. In a system such as define'd in claim 4, 'a water supply line connected into the air supply line between said cut-off valve 'and said three-Way 'p'roportioning valve.

, 6. In a system such as defined in claim '5, said air supply lines in the two assemblies being interconnected for parallel supply from a common source, and said water supply lines likewise being interconnected and having check valves to prevent compressed air from backing up the water in the water supply source.

7. In a system such as defined in claim 6, and a water supply valve and fiowmeter connectedbe'tween the water supply source and said water supply lines for measuring the volume of water supplied to a mix batch in the tank being replenished While the other tank -'is being used.

8. In a system such as defined in claim 4, a main air supply line connected to both air supply lines and having means for regulating the pressure of the air supply to said supply lines.

9. In a system such as defined in claim 7, a main air supply line connected to both air supply lines and having means for regulating the pressure of the air supply to said supply lines.

10. In 'a system such as defined in claim 8, saidpreksure regulating means including a supply valve having a chamber and automatically responsive to the pressure in said chamber, a compressed air line connected to said chamber, a manually controlled valve in said line, said chamber having an adjustable bleed valve to vary the control pressure in said chamber.

11. In a system such as defined in claim 10, said bleed valve having a tube coupling adapted for connection to a tube extended along the delivery tube to the nozzle position, and a bleed valve mounted at the nozzle and connected to the end of said coupled tube to enable the no zzleman to control the air pressure from his station by adjusting the bleed valve at the nozzle.

References Cited in the file of this patent UNITED STATES PATENTS 

